1. Field of the Invention
The present invention relates to orthopaedic reamers, and, more particularly, to acetabular reamers.
2. Description of the Related Art
Minimally invasive surgical techniques have the advantage of reducing the trauma to tissue surrounding the surgical site during a surgical procedure. The small incision that surgeons are using for minimally invasive hip surgery make it difficult to insert a current full size hemispherical acetabular reamer through the small incision. However, the full size hemispherical acetabular reamer cuts a full hemispherical shape in the acetabulum with minimal wobbling and therefore provides an excellent preparation for the hip joint prosthesis. Additionally, a reamer is required to be connected to a driver, which is in turn connected to a rotational tool. The driver has a specific structure at the proximal (to the surgical site) end thereof, which is compatible with specific attachment mechanisms on the reamers. The drivers represent an investment on the part of the medical institution, and if the reamer is modified to be more compatible with minimally invasive surgical techniques, the driver may be correspondingly modified, which necessitates the purchase of both the driver and the reamer for the medical institution. The purchase of a driver adds cost to the acquisition of the new reamer technology.
Orthopaedic reamers are known that cut off opposing segments of the hemispherical shell of the reamer. The resulting reamer, while having a reduced profile in a certain orientation, is no longer rotationally symmetric. The lack of rotational symmetry can cause vibration and wobbling of the reamer when in use. Such a cut-down reamer design can cut an irregular cavity in the acetabulum, for example, during hip joint prosthesis. An irregular cavity in the acetabulum can reduce the expected lifetime of the hip joint prosthesis, cause discomfort for the patient and increase the wear in the artificial joint, among other problems.
An orthopaedic reamer and driver for minimally invasive surgery are known where the reamer, when attached to the driver, can be rotated from a position where the base of the reamer is approximately parallel to the driver shaft for insertion, to a position where the base of the reamer is approximately perpendicular to the driver shaft for reaming. The reamer is generally a one-piece unit. There are cutouts in the hemispherical shell to allow the reamer to rotate over and clear the driver for a minimal insertion profile. The hemispherical shell includes attachment elements for connecting to the driver where these attachment elements are indentations made in the shell of the reamer. The insertion profile of the reamer is reduced by a pivoting of the reamer, which pivoting is accomplished with a specialized driver.
What is needed in the art is an orthopaedic reamer with a reduced insertion profile, of a reliable design and compatible with an existing driver design, in minimally invasive surgery consistent with the small incision thereof.